Manufacture of artificial filaments, ribbons, films, and like materials



H. DREYFUS Jan. 3, 1939.

MANUFACTURE OF ARTIFICIAL FILAMENTS, RIBBONS, FILMS, AND LIKE MATERIALSFiled Feb. 4, 1936 F/GZ 5 U S u & w mm D 6 w A w A A M. W \e H 0 vPatented Jan. 3, 1939 UNITED STATES MANUFACTURE OF ARTIFICIAL FELAMENTS,RIBBONS, FHLMS, AND LIKE MATERIALS Henry Dreyfus, London, EnglandApplication February 4, 1936, Serial No. 62,332 in Great Britain March20, 1935 12 Claims.

This invention relates to improvements in the manufacture of artificialmaterials and is more particularly concerned with new processes for themanufacture of filaments and threads of cellulose acetate or otherorganic derivatives of cellulose or other organic thermoplastic filamentforming substances. The process is also valuable for the manufacture ofribbons, foils, films and like materials from said substances.

According to the present invention, filaments, threads, ribbons, foils,films and the like of the above character are manufactured by spinning asolution of the cellulose derivative or of other organic thermoplasticfilamentor film-forming 15 bases into steam under pressure at atemperature of above 100 C. so as to produce an evaporation of thesolvent content of the solution and, at

the same time, to maintain the structural conti-,

nuity of the filaments, foils, etc. It is of great advantage that thesteam be wet or just saturated, and it is also important that itstemperature should be adjusted so as not to destroy the continuity ofthe structure. Thus generally the temperature should be at least as highas that necessary to render the cellulose derivative or other baseplastic. In the case of acetone-soluble cellulose acetate thetemperature is preferably above 120 C.

If a solution of cellulose acetate in acetone be spuninto a chamber intowhich steam is injected at atmospheric pressure, the steam cools and theresult is either a discontinuous mass om material, or filaments or otherproducts which are delustred and are discontinuous in structure. If,however,

"the temperature of the steam be increased. preferably while maintainingthe steam wet or just saturated, a point is reached at which thestructure of the filament or other material remains continuous. Theproduct may be of moderate or 40 high lustre and in addition aconsiderable drawdown may be applied to the filaments or other materialswithout breakage.

The process of the present invention presents very substantialadvantages over the existing manufacture of such materials. Evaporationof a given volatile solvent may be effected in a much shorter time andconsequently much shorter spinning chambers may be used and/or muchhigher spinning speeds attained. Further, a proper adjustment of thetemperature of the steam in relation to the particular dope which isbeing spun enables a very considerable draw-down to be applied duringthe manufacture of the filaments or other materials, and in consequencefilaments or other materials of very high tensile strength may beproduced. In addition, the new process is of great advantage from thepoint of view of solvent recovery. The spinning chambers need only beprovided with suitable condensing apparatus to enable the solvent to bereadily recovered With- 0 out the aid of elaborate solvent recoveryplant.

As previously indicated, it is highly advantageous for the purpose ofthe present invention to employ the steam in a saturated or wetcondition and to employ it at a temperature well above the boiling pointof water at atmospheric pressure. Thus, for instance, the steam may beat a temperature of 0., C., C. or C. or more, and at the appropriatepressure for the steam to be saturated or wet, such as 10, 20, 30 poundsor more per square inch above atmospheric pressure. The best conditionsare dependent upon the particular dope which is being spun, includingthe particular cellulose derivative or 20 other filamentor film-formingbase, and the nature of the volatile solvent, upon the rate of spinningand upon the degree of stretch which is being applied during thespinning.

The steam may contain vapours of acetone, di- 25 oxane or other volatilesolvent or softening agent for the cellulose derivative or otherfilamentor film-forming base and the presence of such vapours may lowerthe temperature at which it is necessary to operate to secure the bestphysical 80 properties in the products. Generally quite low proportionsof vapour are sufiicient for this purpose, for example proportions byvolume of less than 10% and preferably under 5%.

The process of the invention may be carried out 35 in a spinning cell orchamber adapted to with stand pressure, and for this purpose a tubularchamber is best, spinning nozzles or slits being provided at one end ofthe chamber. The chamber is also provided with means for supplying 40steam under pressure, and with means for with drawing steam containingthe vapours of the volatile solvent. Preferably the chamber is furtherfitted with a pressure gauge, a pressure relief valve and a drain pipefor condensed steam. It 45 is preferred to wind the filaments or otherproducts outside the chamber, and the size of the outlets for thefilaments etc. is preferably adjusted so that escape of steam is reducedto a minimum. The steam inlets may be arranged at any suitable 50 pointsin the spinning chamber, though it is preferred to admit some saturatedor wet steam in the neighbourhood of the spinning nozzles.

The spinning nozzles may be arranged with respect to the spinningchamber so that they are be just inside the chamber or terminate at oneend of the chamber, so as to avoid substantial heating of the dope bythe pressure steam in the chamber, and filter candles, pumps and otherdevices associated with the extrusion devices may be located entirelyoutside the spinning chamber, or alternatively the filter candle andextrusion device may be so adjusted with respect to the spinning chamberthat any desired degree of heat is imparted by the steam to the dope.

The most advantageous arrangement is to have the extrusion device justprojecting into the steam chamber and to have the remainder of theextrusion device and its associated filter candle, with or without thespinning pumps or other devices for delivering the dope to the extrusionorifices in a regulated quantity, in a separate chamber where the dopemay be suitably attemperated before spinning. The separate chamber maybe supplied with water, oil or other attemperating fluid to bring thedope to the required temperature at the spinning point. Such anarrangement is illustrated, in conjunction with ordinary cells forspinning into air, in U. S. application S. No. 375,151 filed July 1,1929. Alternatively, the filter candle may be jacketed so as toattemperate the spinning dope.

In Working the present invention, for example by spinning a solution ofcellulose acetate into steam under pressure, the spinning operation maybe started in air at atmospheric pressure to facilitate leading thefilaments or other materials out of the spinning chamber, and the airmay be replaced by the steam under pressure. The spinning apparatus maybe provided with any of the usual devices in the art, such as a godet tocontrol the draw-down and suitable winding apparatus or twisting andwinding apparatus for the filaments or other materials.

The present invention further includes a process in which the spinningis carried out partly in air or other gas and is continued in steamunder pressure. For example, spinning may be conducted in the usual wayuntil the filaments or other materials are solid but have not beendeprived of all their solvent, and the solventcontaining filaments orother materials then carried into a steam chamber where they may bestretched and the remainder of the solvent re- 1 moved therefrom. Thespinning cell may, for

example, be partitioned so as to contain air or other gas in the portioncarrying or containing the extrusion device and so as to contain steamunder pressure in the portion remote from the extrusion device. Hereagain, the entire spinning operation may be started in air or similargas and the air or other gas in the portion of the chamber remote fromthe nozzle replaced by steam.

In order to avoid injection of the steam from the steam chamber into thechamber in which the dope is actually extruded, the air or other gas inthe latter chamber may itself be under pressure, preferably at apressure substantially equal to the steam pressure. In this form of theinvention, the orifices leading from the air or gas chamber to the steamchamber, as Well as the outlet orifices from the steam chamber, may bemade adjustable so as to be capable of being closed somewhat afterspinning has been start- As previously indicated the new process enablesvery considerable draw-down to be applied.

to the filaments and like materials. The tension for producing thedraw-down may operate upon the more or less solidified filaments or likematerials directly from the extrusion device or means may be adopted,such as a gate tension device, to restrict the tension or part of thetension to portions of the filaments or other materials in the laterstages of the spinning operation.

The process of the present invention may be applied to the manufactureof filaments, threads, ribbons, foils, films and the like of celluloseacetate, or of any other organic ester or ether of cellulose, forexample cellulose formate, cellulose propionate, cellulose butyrate,cellulose nitro-acetate, methyl, ethyl or benzyl cellulose, or otherorganic filamentor film-forming bases, for example poylvinyl acetate andother polyvinyl compounds. The filamentor film-forming base may bedissolved in any suitable volatile solvent, for example acetone, methylethyl ketone or other ketones; methylene ethylene ether, dioxane orother cyclic ethers; or methylene chloride, ethylene chloride,chloroform, tetrachlorethane or similar chlorinated hydrocarbons ormixtures thereof with small amounts of alcohol.

The boiling point of the solvent used in the dope may, where it isdesirable, be suitably related to the temperature of the steam used inthe spinning cells. Thus where the temperature of the steam isconsiderably above the boiling point of the solvent, say 30 C. or more,there may be a tendency towards the production of hollow filaments orlike products, so that, by a suitable correlation of the boiling pointof the solvent with the steam temperature, completely solid filamentsmay be produced or filaments which are more or less hollow orvoluminous.

The water-soluble solvents may, in general, be separated from thecondensate by a simple distillation process. Water-insoluble solventspresent the advantage that they separate from the water in the condenseras a separate layer and may be drawn oif for direct re-use.

The accompanying drawing illustrates suitable forms of apparatus forcarrying out the process of the invention, Fig. 1 illustrating anapparatus in which the entire spinning operation is carried out in steamunder pressure, and Fig. 2 an apparatus in which the first part of thespinning operation is conducted in compressed air and the remainder insteam under pressure.

Referring to Fig. 1, a chamber 3 is fitted with a supply pipe 4, filtercandle 5 and spinning jet 6. The filaments l, extruded from the jet 6,pass down the tubular cell 8 inside a casing 9 forming an extension ofthe chamber 3 and constituting therewith an outer chamber enclosing thecandle 5 and jet 6 and the cell proper 8. The filaments leave the cell 8through a perforation in a closure plate [0 and pass thence to the godetll and are twisted and wound by means of a cap spinning device 12. Thecell B is supplied with steam from a main l3 through branch pipes l4fitted with valves 15, the steam being injected into the cell 8 throughperforated annular pipes IS. The cell 8 is provided with a pipe I!fitted with a valve i8 for Withdrawing steam containing solvent vapours,with a valved drain pipe I9, a pressure gauge 20, and a pressure reliefvalve 2|. Inside the casing 9 are provided steam heating pipes 22.

The upper end of the cell 8 is closed by means of a hood 23 pressed downupon a pad of packing material 24 and making a tight joint with atubular member 25, fitting round the filter candle 5. Access to thespinning jet 6 is obtained through a door 26 in the chamber 3 and byunscrewing and raising the hood 23. A jacket 4'! is provided roundthefilter candle 5 and is fed with an attemperating fluid passing from amain 2! through a valve 28, through an inlet pipe 29 into the jacket,and out by a pipe 3!] and valve 3| into an exhaust main 32. The chamber3 is further provided with a suction draw-ofi 34.

In starting up the apparatus, the closure plate ii! is opened slightly,steam turned'on in the heating pipes 22, and the hood23 raised. A slowcurrent of air is sucked through the apparatus by means of the suctionpipe 34, the heated air traversing the cell 8 serving to evaporatevolatile solvent so that by the time the filaments reach the foot of thecell they aresuificiently solid to be handled. The spinning thusstarted, the fila ments are threaded through the outlet hole in theplate it, and the plate screwed in position. Steam is then turned onslowly into the cell 8, the valve l8 being slightly open, and the hood.23 screwed down to make a pressure tight joint with the pad 24. Thesteam is turned off from the pipes- 22, and the steam pressure in thecell 8 gradually increased, the filaments being drawn out more and morerapidly from the chamber. When the desired spinning speed is attained,the filaments are carried round the godet roller H and thence to the capspinning device I2.

Referring to Fig. 2, the filter candle 5 is con tained in a chamber 35forming an enlargement of the upper end of the tubular cell. The latteris formed in two parts 36, 31, the upper part 36 being surrounded by achamber 38 forming an extension of the upper chamber 35, and providedwith heating pipes 22. Access to the spinning jet 5 is obtained througha door 39 forming a gas tight joint on a gasket 40. The spinningsolution passing through the candle 5 is heated by means of a heatingcoil 4| connected to the supply and exhaust headers 21 and 32 forheating the fluid. Between the parts 38 and 31 of the tubular cell, aperforated plate 42 is provided. The upper part 35 of the cell isprovided with a valved inlet 43 for compressed air and a pressure gauge44.

In operation the spinning is started up in air at atmospheric pressure,as described with reference to Fig. 1. When spinning is well started,the filaments are threaded through the plate 42 and the closure plateHi, and the lower part 31 of the cell fixed in position. Compressed airis then turned on through the pipe 43 and steam through the pipe l3 sothat the lower part 31 of the cell is filled with steam under pressure,and the upper part of the cell 35 and the upper chamber 35 filled withcompressed air. Steam and solvent vapour escape as before through thepipe ii, and air and solvent vapour through the pipe 34.

If desired, either in the apparatus illustrated in Fig. 1 or in thatillustrated in Fig. 2, a gate tension device may be provided so as toprevent all or part of the tension being operative upon the filamentsfor the whole of their travel through the cell. Such a device isillustrated at 4-5, Fig. 2.

The following examples illustrate the invention but are not to beconsidered as limiting it in any way.

Example 1 A 25% solution of cellulose acetate in dioxane is spun intofilaments, using either the apparatus illustrated in Fig. 1 or thatillustrated in Fig. 2. In both cases the pressure of the steam isadjusted so that its temperature is 125-135 C. and the steam is justwet, and in the case of Fig. 1 they dope temperature is adjusted so thatit is mil-105 C. In the case of Fig. 2, the air temperature and the dopetemperature are both adjusted to this figure.

Example 2 A 20-24% solution of cellulose acetate in the monemethyl etherof ethylene glycol is spun as described in Example 1, with the steamtemperature at l-135 C.

Example 3 The process is carried out as in Example 2, with the exceptionthat the spinning solvent consists of 80 parts of the methyl ether ofethylene glycol and 20 parts of methyl glycol mono-acetate.

Example 4 A 25% solution of cellulose acetate in a mixture of 80% of themonomethyl ether of ethylene glycol and 20% of acetone is spun asdescribed in the preceding examples, the temperature of the steam being120-125 C. and the steam is just wet.

In all cases, a very considerable draw-down is obtained and thefilaments of medium to high lustre possess a high tenacity.

Having described my invention what I, desire to secure by Letters Patentis:

1. Process for the manufacture of filaments, threads, ribbons, foils,films and the like, which comprises spinning a solution of an organicthermoplastic filamentor film-forming substance into an evaporativeatmosphere which is heated and which is maintained undersuperatmospheric pressure, said evaporative atmosphere comprising,during at least part of the spinning operation, steam at above 100 C.and at superatmospheric pressure.

2. Process for the manufacture of filaments, threads, ribbons, foils,films and the like, comprising spinning a solution of an organicthermoplastic filamentor film-forming substance in a volatile solventinto steam at above 100 C. and at superatmospheric pressure, and drawingout the products during the spinning.

3. Process for the manufacture of filaments, threads, ribbons, foils,films and the like, comprising spinning a solution of an organicthermoplastic filamentor film-forming substance in a volatile solventinto heated air at superatmospheric pressure and before the volatilesolvent is removed carrying the products into steam at above 100 C. andat superatmospheric pressure, and drawing out the products.

4. Process for the manufacture of filaments and threads of organicderivatives of cellulose, which comprises spinning a solution of anorganic derivative of cellulose in a volatile solvent into wet orsaturated steam at above 100 C. and at superatmospheric pressure, anddrawing out the products.

5. Process for the manufacture of filaments and threads of celluloseacetate, which comprises spinning a solution of cellulose acetate in avolatile solvent into wet or saturated steam at above 100 C. and atsuperatmospheric pressure, and drawing out the products.

6. Process for the manufacture of filaments and threads of celluloseacetate, which comprises spinning a solution of cellulose acetate in avolatile solvent into wet or saturated steam at above 120 C. and atsuperatmospheric pressure, and drawing out the products.

7. Process for the manufacture of filaments and threads, which comprisesspinning a solution of cellulose acetate in a volatile organic solventhaving a boiling point of C. or above into Wet or saturated steam at atemperature above C. and at superatrnospheric pressure, and drawing outthe products.

8. Process for the manufacture of filaments and threads, which consistsin spinning a solution of cellulose acetate in a volatile solvent havinga boiling point of 100 C. or above into heated air at superatmosphericpressure and thence into wet or saturated steam at above 120 C. and atsuperatmospheric pressure, and drawing out the products.

9. Process for the manufacture of filaments and threads, which consistsin spinning a solution of an organic derivative of cellulose in avolatile solvent into wet or saturated steam at above 100 C. and atsuperatmospheric pressure, and drawing out the products while preventingthe whole drawing tension from operating upon the materials at the pointof extrusion.

10. Process for the manufacture of filaments and threads, which consistsin spinning a solution of cellulose acetate in a volatile solvent intowet or saturated steam at above 100 C. and at superatmospheric pressure,and drawing out the products while preventing the whole drawing tensionfrom operating upon the materials at the point of extrusion.

11. Process for the manufacture of filaments and threads, whichcomprises spinning a solution of an organic derivative of cellulose in avolatile solvent into heated air at superatmospheric pressure and thenceinto wet or saturated steam at a temperature above 100 C. and atsuperatmospheric pressure, and drawing out the products while preventingthe whole drawing tension from operating upon the materials at the pointof extrusion.

12. Process for the manufacture of filaments and threads, whichcomprises spinning a solution of cellulose acetate in a volatile solventinto heated air at superatmospheric pressure and thence into wet orsaturated steam at a temperature above 100 C. and at supera'tmosphericpressure, and drawing out the products while preventing the wholedrawing tension from operating upon the materials at the point ofextrusion.

HENRY DREYFUS.

CERTIFICATE, OF CORRECTION. Patent No. 2,1L .2,l2l'. I January 5, 1959.

HENRY DREYFUS;

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correotionas follows Page 1,first column, line 52, for "om" read of; page 5, second column, line 17,Example 2, after "155 0." insert the words and period and the steam isjust wet.;

and that the said Letters ,Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 21st day of February, A.-D. 1959.

Henry Van Arsdale (seal) Acting Conmaissioner of Patents.

